Posted by Larry Hoover on February 9, 2003, at 22:31:25
In reply to Placebo Responders Dropped? » Larry Hoover, posted by fachad on February 9, 2003, at 18:35:23
> > >During trials, apparently they give placebos first, then eliminate those test subjects who are affected by the placebos, thus sever3ely skewing the results.
> >
> > That's simply not true. That would not be double-blind.
>
> I'm sure I've read many studies where early responders, whether responding to the active agent, or the control, or the placebo, are dropped from the study.
>
> This is supposed to make the results more valid, by eliminating placebo responders so that all the results are from actual drug effects, vs. placebo response.It would certainly enhance the statistical significance, but I cannot think of an acceptable rationale for doing so. Post hoc data selection is nothing more than falsifying outcomes, in my mind. Do you have any kind of reference or example? I can't think of a case, myself.
The only post hoc selection process that I can think of off the cuff is called intention-to-treat analysis, but it actually makes it harder to obtain statistically significant results, not easier.
poster:Larry Hoover
thread:140316
URL: http://www.dr-bob.org/babble/20030208/msgs/140383.html